Personal Information Devices include the class of computers, personal digital assistants and electronic organizers that tend both to be physically smaller than conventional computers and to have more limited hardware and data processing capabilities. PIDs include, for example, products sold by Palm, Inc. of Santa Clara, Calif., under such trademark as Pilot, and Pilot 1000, Pilot 5000, PalmPilot, PalmPilot Personal, PalmPilot Professional, Palm, and Palm III, Palm V, Palm VII, as well as other products sold under such trade names as WorkPad, Franklin Quest, and Franklin Convey.
PIDs are generally discussed, for example, in U.S. Pat. Nos. 5,125,0398; 5,727,202; 5,832,489; 5,884,323; 5,889,888; 5,900,875; 6,000,000; 6,006,274; and 6,034,686, which are incorporated herein by reference. PIDs typically include a screen and data processor, allowing the PID user to operate a substantial variety of applications relating to, for example: electronic mail, a calendar, appointments, contact data (such as address and telephone numbers), notebook records, a calendar, expense reports, :to do lists: or games. PIDs also often include substantial electronic memory for storing such applications as well as data entered by the user. Due to their substantial variety of applications and uses, personal information devices are becoming increasingly widely used.
One important characteristic of personal information devices is the easy manner in which software applications and information are made available to the user. Many PIDs are equipped with touch screen displays. The touch screen displays are used to implement various user input and output schemes. Since PIDs and other similar palmtop computer systems are very small, keyboards are generally not efficient input devices. For example, PIDs with keyboards have keyboards that are so small that a user cannot touch-type. Furthermore, to use a keyboard a user must either place the PID system down onto a flat surface so the user can type with both hands or hold the PID system with two hands and type with thumbs only.
Thus, instead of using a keyboard, many PIDs employ a stylus and a touch screen or digitizer pad as an input system. The stylus and touchscreen combination works well for PIDs since the arrangement allows a user to hold the PID system in one hand while writing with the stylus onto the touchscreen with the other hand.
There is a problem, however, in that the mechanism for implementing the touch screen functionality tends to interfere with the transmission of light to an underlying display. Typical prior art touch screen displays employ a touch sensor mechanism overlaid on top of a display screen. The touch sensor mechanism detects user touches of its area, and translates such touches into appropriate inputs, such as, for example, icon manipulations, text entry, menu selections, and the like. The touch sensor mechanism is designed to be transparent to allow viewing of the underlying display screen. Unfortunately, prior art touch sensor mechanisms are not perfectly transparent. Prior art touch sensor mechanisms often allow only 60 percent or less of the impinging light to pass through to the underlying display screen. This leads to very dim displays. To overcome this characteristic, some manufacturers employ back lighting or front lighting of the display to compensate for the light attenuation of the touchscreen mechanism. This leads to excessive power consumption, decreased battery life, and overly large touch screen displays.
There exists an additional problem in that by combining a separate touchscreen mechanism and display screen to implement a touchscreen display, a seam necessarily exists between the mechanism and the screen. Although this seam can be sealed, it is still vulnerable to the entry of environment contaminants, such as dust, various liquids, etc. To improve the environmental seal, many manufacturers employ a beveled edge around the outsides of the touchscreen display, enclosing both the touchscreen mechanism and the display. Although the beveled edge improves the seal, environmental contaminants (e.g., dust, etc.) can still make their way around the edge and into the touchscreen display.
Thus, what is required is a solution that eliminates exposed seams of a PID. What is required is a solution which improves the transmission of light through the touchscreen mechanism, thereby improving the visibility of the display. The required solution should be inherently impervious to the entry of particulate contaminants and the like. The present invention provides a novel solution to the above requirements.